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DY: Fachverband Dynamik und Statistische Physik

DY 33: Brownian Motion, Stochastic Processes, Transport I

DY 33.10: Topical Talk

Thursday, March 17, 2011, 16:30–17:00, HÜL 186

Motion States in Intracellular Transport — •Doris Heinrich — Faculty of Physics and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany

The living cell's cytoskeleton is a fascinating active network, in which diffusion is intercepted by distinct phases of directed transport. To dissect temporal phases (i) of active, directed motion of a tracer particle along a cellular filament and (ii) motion in the diffusive regime, a time-resolved statistical mean-squared-displacenment (MSD) analysis was applied. In living amoeba, the distribution of active lifetimes for an intracellular particle, moving along microtubules via ATP-driven biomotors, is found to decay exponentially with a characteristic lifetime of about t=0.5s [1]. However in motor neurons, cellular vesicles show very efficient directed transport for large distances, whereas inserted non-functionalized nanoparticles mostly undergo subdiffusion [2]. To investigate the time-dependent contributions of cytoskeletal components on diffusive motion states in the crowded cellular interior, a local, lag-time dependent MSD analysis was employed. Cellular fine-tuning from Brownian to subdiffusive motion could be extracted, which enables effective interplay of intracellular molecules on the nanoscale. This active actin-microtubule interplay is not only important for intracellular transport, but also contributes to active cellular stability and other cell functions, like cellular migration [3].

[1] PRL101:248103(2008) [2] ChemPhysChem10:2884(2009)

[3] Annu.Rev.Condens.MatterPhys.1:257(2010)